Disclosed herein is the discovery that there are alpha-2B adrenergic receptors on a subtype of T cells, and that alpha-2 receptor agonists may be used to modulate the activity of such T cells and thereby treat those diseases in which T cell dysfunction plays a role, including neuritis, Guillain-Barre syndrome, rheumatoid arthritis, type I diabetes, multiple sclerosis (MS), graft-versus-host disease (GVHD), autoimmune uveitis, ocular inflammation, keratoconjunctivitis sicca (dry eye syndrome), sjogren's syndrome, atopic dermatitis, psoriasis, inflammatory bowel disease, irritable bowel syndrome, asthma, and aplastic anemia.